A bearing apparatus for supporting rotary parts has hitherto been, when once incorporated, subjected to none of periodic inspections in many cases, and in such a case it often happened that an interior thereof was inspected for the first time just when inconvenience occurred due to abnormality in temperature. Further, in the case of the bearings for a railway vehicle, a wind turbine, or the like, the bearing apparatus and other portions are decomposed and inspected after being used for a predetermined period of time. It is therefore difficult to predict the inconvenience due to the abnormality in temperature beforehand. By contrast, there is an attempt for detecting the abnormality in the bearing before critical inconvenience occurs by measuring a change in temperature in a way that fits the temperature sensor to a bearing apparatus (refer to Patent document 1 given below).
[Patent document 1] Japanese Patent Laid-Open Publication No. 2002-130263